Radiation is the transfer of heat or energy from a hot surface to a cold surface through air or a vacuum. For example, radiant heat from the sun travels through space and strikes the roof of a building and exterior walls of a building, causing the roof and exterior walls of the building to increase in temperature. Heat flows from the outer surface of the roof and exterior walls of the building to inner surfaces of the roof and the walls of the building through conduction. If the inner surfaces of the roof and walls of the building are warmer than surfaces inside the building that are spaced apart from the roof and inner walls of the building, heat will radiate from the inner surfaces of the roof and the walls of the building to the surfaces inside the building. Radiation between surfaces inside a building occurs through invisible infrared heat rays.
Heat can also exit a building through radiation. In winter months, surfaces inside a building are often warmer than the inner surfaces of the walls and the roof of the building. Warmer surfaces inside the building radiate heat to the inner surfaces of the walls and the roof of the building, causing them to increase in temperature. This heat flows from the inner surfaces of the walls and the roof of the building to the outer surface of the walls and roof of the building through conduction.
The ability of a material to emit radiant energy and absorb radiant energy is defined by the materials emissivity and reflectivity. The lower the emissivity of a material, the lower the amount of heat that is radiated from its surface. The higher the reflectivity of the material, the higher the percentage of incident radiant heat that is reflected from the material's surface. Radiant barriers and reflective insulation systems reduce radiant heat transfer between surfaces across open spaces, which is a significant contributor to heat gain during warm months and heat loss during cold months. Radiant barriers are a single layer of reflective material spaced apart from a surface which radiates heat. Radiant barriers do not prevent heat on one side of the reflected material from being conducted to the second side of the reflective material. Reflective insulation systems are typically laminate products that reduce heat transferred due to radiation, as well as convection. Reflective insulation systems typically include a reflective layer and a conduction preventing layer. The conduction preventing layer prevents heat on the reflective layer of the reflective insulation system from being conducted to the second side of the reflective insulation system.
Reflective insulation systems are installed such that a reflective layer is spaced apart from the roof decking or the outer wall of a building. Heat that is radiated inward from the roof or outer walls of the building is reflected off the reflective layer of the reflective insulation system back to the roof or outer surface of the building. The temperature of the roof or outer surface of the building increases rather than the interior of the building.
In winter applications, heat radiated by surfaces in the interior of the building are reflected back into the interior of the building if a reflective layer is included that faces the interior of the building. By reflecting radiant heat from the roof and external walls of the building back to the roof and outer walls of the building the heat that enters the building is reduced during warm months. By reflecting the heat radiated by the interior surfaces of the building back to the interior surfaces of the building, the heat that escapes from the building is reduced during cold months.
Numerous reflective insulation products are currently available. However, a need continues to exist for methods of forming reflective insulation products that are efficient and cost-effective. Reflective insulation products formed by utilizing such methods would be particularly beneficial.